Conventionally, the mouth of a thermos or other fluid containers is firmly press-fitted with a plug for preserving the warmth or for preventing leakage of the content. If the content is to be discharged, the plug has to be detached from the container by turning it. However, such a conventional container is accompanied with an inconvenience of detaching the plug from the container each time it is used.
Meanwhile, there is a method in which the plug is released to open the whole or a part of the discharge hole for overcoming the above described inconvenience. In this method, however, the direction of the discharge hole has to be checked before discharging the content, and if it is not checked, the contents may spill. Further, in this method also, the plug can be opened only by turning it, and therefore, the plug has to be fitted firmly. Therefore, turning the press-fitted plug is very inconvenient.